1. A transmitter comprising:
a modulation unit to generate modulation symbols by modulating a transmission bit sequence;
a coding unit to generate coded symbols by performing differential space-time block coding on the modulation symbols;
a conversion unit to perform, on the coded symbols, a conversion process selected from among a plurality of conversion processes; and
an antenna to transmit the coded symbols after the conversion process.
2. The transmitter according to claim 1, wherein a plurality of the antennas is provided, and
the conversion process to be performed on the coded symbols is selected for each of the antennas corresponding to the coded symbols.
3. The transmitter according to claim 2, wherein
four conversion processes are defined in advance for each of the antennas, and
the conversion unit performs, on the coded symbols, a conversion process selected from among the four conversion processes corresponding to each of the antennas.
4. The transmitter according to claim 3, wherein the four conversion processes are a process of
outputting the coded symbols as they are, a process of inverting positive/negative signs of imaginary parts of the coded symbols and then exchanging real and imaginary parts, a process of inverting positive/negative signs of real and imaginary parts of the coded symbols, and a process of